Conrad Black, the disgraced British peer serving a 6½-year sentence in Florida for defrauding millions from his former media empire, has asked President Bush to grant him clemency before leaving the White House.

The US justice department has confirmed that it is considering the request. An agreement by the president could involve either pardoning the offence, which would erase the criminal record, or commuting it.

Black, 64, was chairman and chief executive officer of Hollinger International the third largest media empire of its day, for eight years. It included titles such as the Daily Telegraph, the Jerusalem Post and the New York Sun.

He quit the company in 2003 after he was found to have received millions of dollars in unauthorised payments. In 2007 he was convicted, with three other Hollinger executives, of four counts of fraud amounting to $6.1m (£4m) and of obstructing the course of justice. He began his sentence in March at a prison in Coleman, Florida.

The Sun-Times Media Group, the company that emerged from Hollinger International, has been taken aback by the clemency application, because Black always insisted he would not make any such request. The firm was even more surprised when lawyers acting on behalf of the jailed tycoon submitted legal bills to his former business asking for it to pay for costs incurred in the clemency plea.

One unnamed source at the company told the Toronto-based Globe and Mail newspaper: "We try to draw the line at outrageous things, and this is sort of one of them."

More than 5,000 applications for pardon and commutation are waiting to be processed by the justice department.

Black told the Globe and Mail this month that he was "horrifyingly busy with one thing and another" in jail. When the paper asked what was taking up all his time, he replied: "Writing and reviewing legal initiatives, as well as dealing with my students" - an apparent reference to the history seminars he is said to be running.